Safety Systems and Internal Events PRA (Task 1)

Task Overview

Objective

Determine the systems required to provide protection for seismically induced initiating events.

Purpose

This step identifies the systems to be considered for the SPRA. Typically, this is performed by starting with the Internal Events (IE) PRA model which has already considered the important accident sequences and system responses. The IE model is then modified as necessary to account for seismic events.

If an internal events PRA does not exist, a new SPRA model can be created by considering the scope of potential seismic induced failures and systems necessary to respond to those accidents.

Guidance

The Internal Events PRA task typically addresses the following issues:

• Satisfying the requirements of the ASME/ANS PRA Standard
• Sequence development in the internal events PRA is sufficient for Level 2 assessment

Supplemental Guidance

Related Element of ASME/PRA Standard

Part 5, Seismic Plant Response Systems Analysis (SPR-A and SPR-C)

• The internal events model typically has addressed the Part 2 (Internal Events PRA) requirements for Accident Sequences (AS), Success Criteria (SC), Systems Modeling (SY), Data (DA), Human Reliability Analysis (HR), Quantification (QU), and LERF Analysis (LE)

EPRI Guidance

Seismic Probabilistic Risk Assessment Implementation Guide (3002000709)

Other Guidance

NUREG/CR-2300, "PRA Procedures Guide, A Guide to the Performance of Probabilistic Risk Assessments for Nuclear Power Plants" (Vol 1 and 2)